Acetylcholine and choline concentrations and acetylcholine turnover rate were measured in different regions of rat brain during anesthesia with halothane, enflurane and ketamine. None of the anesthetics significantly changed acetylcholine and choline concentrations in different parts of the brain. Halothane decreased the acetylcholine turnover rate in all parts of the brain. Enflurane decreased the turnover rate only in the cortex. Ketamine caused no significant change of turnover rate in the cortex but decreased the turnover rate in the caudate and the hippocampus. The results suggest changes in the turnover rate are related to anesthetic induced electrophysiological changes in cortical and subcortical structures.